Washing the blueberries will destroy that natural layer of protection, so it's best to wait until the day you plan to use them to give them a quick rinse. If you do choose to wash blueberries before freezing, be sure they are completely dry before freezing. Excess moisture could lead to bacteria, mold and rot.
If you choose to not wash your blueberries before freezing, you'll be able to preserve the waxy “bloom,” which is a natural protective coating on the berry that protects it from insects and bacteria.
Before freezing, remove any berries that are immature, moldy or discolored. To wash berries, place in a colander and submerge two or three times in a sink full of cold water. Drain well.
Most berries should not be washed until they are being used. Excess water can cause premature spoilage for delicate, antioxidant-rich fruits like blueberries and raspberries, even gooseberries.
Even organic berries should be washed before eating; while there may not be chemicals to rinse off, there's still dirt and other grime to be cleaned off before you use the berries for anything.
In recent years, people have developed foodborne illnesses from fruits and vegetables. Cooking produce before consumption is the safest way to eat fruits and vegetables, but people should still wash them beforehand. Many farmers use pesticides on their produce.
The American Frozen Food Institute (AFFI) clarifies that frozen fruit is safe and ready-to-eat straight from the package, no need to wash it. This is due to its higher levels of acidity and sugar, making it unlikely that harmful bacteria could grow on it at freezer temperatures.
The secret to freezing blueberries without them getting that mushy texture is to let them fully dry after washing and let them chill on a baking sheet (or cookie sheet) in the freezer before storing in airtight containers.
Washing them before freezing can cause the skins to get tough if there is any moisture left on them. The second way to freeze blueberries is crushed or pureed. For this process you wash the berries first then use a food processor, blender or sieve to crush or puree them.
Just remember to rinse the berries before using them. Commercially frozen blueberries have been washed—use them directly from the bag. Refrigerate thawed blueberries and use within 3 days. Use any frozen blueberries within one year of purchase.
To dry berries after washing, carefully spread them in a single layer on a tray or baking sheet lined with paper towels. Gently pat the berries dry with another paper towel.
Since blueberries are frozen soon after they are picked, “they are equal in quality to fresh,” Plumb explains. She analyzed the anthocyanin content of blueberries frozen for one, three, and five months and found no decrease in antioxidants over fresh berries.
When serving frozen fruits for dessert, serve them while there are still a few ice crystals in the fruit. This helps compensate for the mushy texture frozen fruits have when thawed.
Frozen fruit is often softer and sweeter than fresh fruit. This is because the water in the fruit expands when it's frozen, making the cells burst, resulting in the release of the natural sugars.
Don't think a little dirt on 3.5 berries will hurt you much. Eating unwashed produce may cause you to ingest harmful bacteria, which may be present in the soil, or pesticides applied to produce in the fields. What's more, you might even end up eating bugs that were harvested along with the produce.
The Centers for Disease Control and Prevention says washing your produce under running water can prevent you from becoming infected with food-borne illnesses like norovirus, which is the country's leading cause of disease outbreaks from contaminated food.
Wash berries when you're ready to eat them.
Berries readily absorb excess water. If you wash them and then stick them in the refrigerator, they could get moldy or mushy. Keep berries fresh and avoid mold spores by keeping them dry until you're ready to use them.
Rinse with cool water.
Gently wash the berries by setting the faucet on a cool, low temperature and running water over them. Shake the colander or swish the water with your hand to remove residual dirt or pesticide residue.
The vinegar helps to kill any mold that could cause them to spoil, and this method can make them last as long as 10 days in our house! Voilà, that is how you keep berries fresh longer.
To try this editor-approved strategy, combine 1 part white vinegar to 4 parts water (for example, ¼ cup vinegar plus 1 cup water) in a pitcher or bowl, then soak the berries in the vinegar water for about 5 minutes. After that, rinse thoroughly with plain water.
To help prevent food poisoning, do not eat unwashed fresh produce. Wash or scrub fruits and vegetables under running water—even if you do not plan to eat the peel. Germs on the peel or skin can get inside fruits and vegetables when you cut them.
A few moldy berries don't mean you have to throw out the whole batch. Dr. Rajapakse says to throw out the ones that look visibly moldy as well as any that might have been in direct contact. "If more than about a quarter of the berries are moldy, you're probably best off getting rid of all of those berries.